A mega-battle is brewing between corporate giants such as AT&T, Google and Time Warner Cable to build Wi-Fi hotspots in U.S. cities connected to massive gigabit fiber-optic or fast networks of cable providers.

In the coming years, Google -- and likely its competitors-- will pump free or low-cost Internet service to city centers and shopping areas, granting shoppers and other users access to a wide array of the services and advertising that are central to Google's revenue model.

Both AT&T and Google recently announced proposals to provide gigabit fiber services to dozens of U.S. cities, and Wi-Fi connected to the fast fiber is expected to be a part of that offering.

Over the past several years, Time Warner has been busy provisioning its modern cable network to add 11,000 Wi-Fi hotspots for its Internet customers to use for mobile devices in various Kansas City area locales, including stores, parks, walking paths and nightlife spots like the popular downtown eight-block Power & Light District. During the last two years, the Google Fiber network has steadily mushroomed to 6,000 fiber-optic miles throughout the KC metro area, but it hasn't been connected so far to Wi-Fi.

In a 10-page document obtained by the IDG News Service, Google informed 34 cities that are candidates for Google Fiber in 2015 that it will be "discussing our Wi-Fi plans and related requirements with you as we move forward with your city during this planning process."

Google, in part, appears to be responding to AT&T's history of supporting up to 34,000 Wi-Fi hotspots nationwide. For instance, AT&T runs a Times Square "hotzone" in New York City as well as hotspots in other city centers and restaurants that can be used without charge by select AT&T home Internet customers who are going mobile with smartphones and tablets.

The prospects are that AT&T will expand its Gigapower 1 Gbps fiber-optic offering to include Wi-Fi in 21 cities, potentially adding new services, paid for by end-users or third parties. And for Google, the potential for Wi-Fi atop of Google Fiber "is all about market creation for new kinds of ads and services," said Patrick Moorhead, an analyst at Moor Insights & Strategy.

"The fatter the pipe -- whether via fiber or Wi-Fi connected with fiber -- more of the user experience can be delivered via a remote data center, which is a strategic advantage for Google," Moorhead added. "Google could put ads on everything from billboards to smart mirrors to the sides of buildings much, much easier."

"Also, pervasive, fast connectivity means you can have more dumb clients that get all their horsepower from the cloud as a service," he added.

Jack Gold, an analyst at J. Gold Associates, said even AT&T's reliance on Wi-Fi in many locations hasn't been sufficient to handle the coming bandwidth load of uses, especially for video over Netflix, YouTube and video used in ads.

"As users increase their use of rich media, they load up the networks pretty badly, and with an expected 1000x bandwidth increase needed by 2020, there's a real problem," Gold said.